Sure!
For starters, Kudos for solving a good number of problems — that gives you a fair foundation to build upon. Interestingly, while I've mentioned earlier that you're expected to solve ~200 problems in the [Rating-200:Rating+200] range which would place you higher; your rating is probably suffering from a variety of other factors-

• The cheater wall. Unfortunate as it may be (and I don't really know its current status), as far as I remember, there's a stupid cheater wall around 1700?1800? if you're performing below that, you end up being bashed by a large bunch, and once you're above that, it's smooth sailing.
• Regarding the first point, don't worry about it too much, with practice, you should be able to overcome it, and it was actually a motivator for me personally.
• Consistency in general, I see that your performance fluctuates a lot across contests, solving the number of problems that you have should probably translate to at least a consistent 3 in Div.2s
• A cursory glance at your submissions shows that you're probably not reasoning about your code as much as you should. I'll elaborate on this — basically, it's a pattern that I've noticed among a lot of contestants (and was guilty of this myself); you probably think of a "direction" for the problem, a "hunch" if you will, and dive into implementation head-first; half-way in (or maybe after failing tests) you realize there's an issue! You patch it, repeat, find another issue, and so on, so forth — ending up working with spaghetti code. This ends up with a frustrating cycle that consumes a lot of time (and yields high penalty). If that's the case, then maybe an advice that helped me could help you-
  Learn to reason about your code more. It takes time; maybe write down the logic (especially in case of DP, do write down the states/transitions), and at every step, reason about the information (data) you have and the operations you can perform on it (sort/search/etc), build your solution step by step, and then once you're confident, only then, start implementing.
  This can probably be hard to digest, and it sucks when you're taking more time solving A/B than others who "guess" solutions, but it oftentimes helps avoid unnecessary penalties (and the patch-cycle); it takes time to adapt (I used to jump to guesswork sometimes myself), but in the long-run, once you're used to it, it's a great help, you also learn to reason about your code better and write clean code (spaghetti free!) which saves a lot of time on harder problems
• Towards writing cleaner code in general — read top contestants' solutions, they often implement ideas in a much cleaner way and adopting such practices helps get rid of a lot of "clutter" that you would otherwise inculcate into your code.
• For other tips, refer this; it helped me, hopefully it helps you as well.

Yes I did, you can check my (or others') Atcoder activity through Kenkoooo